Method of and apparatus for drawing sheet glass



Jul 8, 1-924. v1,500,331

R. L. FRlNK ET AL METHOD OF AND APPARATUS FOR DRAWING SHEET GLASS Filed Jan. 14 1920 2 Shaets Sheet l INi EMDRJ Taber [7521A find-775d ITEM.

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July 8 1924.

. 1,500,381 R. L. FRINK ET AL METHOD OF AND APPARATUS FQB ISRAWIkG SHEET cuss Filed Jan. 14. 1920 2 sneaks-sheet 2 ATTORNEYQS.

Patented July 8, 1924.

UNITED STATES 1,500,381 PATENT OFFICE.

ROBERT L. FRINK AND FRED J. FRINK, OF LANGASTE, OHIO.

METHOD OF AND APPARATUS FOR DRAWING SHEET GLASS.

Application filed January 14, 1920. Serial No. 351,380.

T 0 all whom it may concern:

Be it known that we, ROBERT L. FRINK and FRED J. FRINK, citizens of the United States, and residents of Lancaster, county of Fairfield, State of Ohio, have jointly invented a new and useful Improvement in Methods of and Apparatus for Drawing Sheet Glass, of which the following is a specification, the principle of the invention being herein explained and the best mode in which we have contemplated appl ing' that principle, so as to distinguish it om other inventions;

The object of the present invention is to adapt an electrically heated bait, such as one of the present inventors has heretofore perfected for use in drawing glass cylinders, to the drawing of glass in sheet form directly. Several constructional forms of bait for drawing glass cylinders are shown in United States Letters Patent 'No. 972,615, granted to R. L. Frink under date of October 11", 1910, including a support and a metallic band secured at separated points along one edge of said support whereby said band may contract and expand relatively to said support, means being provided for pa$ing a heating electric current through such band so as to maintain the bait during the draw above the second point of tension in the glass, that is, above the point where the glass comes to a set. The adaptation of a bait of this type for use in. drawing glass sheets in contradistinction from glass cylinders obviously presents numerous difiiculties, the principal one being the tendency for the edges of the sheet to draw together, and so gradually narrow the width of the sheet as'it is drawn from the bath of molten metal. It is also necessary to correlate the speed of the draw with the viscosity of the surface of the bath, asby providing re-' quired and predetermined heat insulating walls about the bath and in such relation to the sheet to be drawn as will render such sheet of proper thickness throughout its transverse extent. v

To the accomplishment of the foregoing and related ends, the invention consists of the steps and means hereinafter fully des ribed and particularly pointed out in the claims, the annexed drawings and the following description setting forth in detail certain means and one mode of carrying out the invention, such disclosed means and mode illustrating, however, but one of various ways in which the principle of the invention may be used.

In said annexed drawings; Fig. 1 is a front elevational view of an apparatus embodying our present improvements, and illustrating one form of means adapted to carry out our improved, method or process for drawing sheet glass; Fig. 2 is a side elevation of the same; Fig. .3 1s a plan view of the pot for molten metal; andFig. 4 is a view more or less diagrammatic in character showing the manner in which the sheet after being drawn is lowered and successive sections severed therefrom.

The drawing pot, as best shown in Fig. 3, comprises an outer shell 1, within which is mounted a shallow clay vessel 2 that constitutes the drawing pot proper, such'vessel being spaced from the outer shell 1 and such space filled with suitable insulating material 3, as shown in Fig. 1. One or more drain openings 4 are provided in the bottom of the vessel 2, a suitable plug 5 serving to normally close such opening when the drawing pot is in use. For the purpose in hand it is not deemed necessary to show the manner of support of the drawing pot, nor any means for supplying glass thereto. It will be understood, however, except as hereinafter described, no means for heating or otherwise affecting the temperature of the molten metal in the pot during the drawing operation will be employed, and thatsuch metal will be labeled at a predetermined temperature and in measured quantities from the tank to the pot.

The only.temperature controlling means which we contemplate employing are the covers 6, two in number, as shown, which preferably consist of clay blocks movably supported in close-fitting contact with the upper edges of the vessel 2 by means of car riages 7, in which such blocks are held. The wheels 8 of the respective ends of these carriages run on suitable tracks 9 disposed adjacent to, and parallel with, the end walls of the drawing pot, so that the covers may be independently shifted transversely of such pot so as to leave an opening between their adjacent inner edges of any desired width and located as found desirable transverselyof such pot, onthey may be so separated as to completely uncover the pot.

Arranged so as to be supported directly over the opening thus left between the covers 6, and adjacent the respective ends of the path of molten glass in vessel 2 are electrically heated shoes 10, having the form clearly shown in Figs. 1 and 2. In other words, these shoes have their inner faces convex in a yertical direction, being preferably straight across in a transverse direction. Such shoes are provided with individual self-contained resistance elements,

the detailed construction of which it is not In order to support the shoes 10 in proper position over the space between the inner edges of the cover 6, as also at a variable elevation with respect to said covers, or rather the surface of the bath of molten glass in the drawin pot, we provide horizontal arms 15, in t e outer ends of which said shoes are clamped, while at their inner ends said arms are attached to brackets 16 threaded on a shaft 17 and guided on a parallel rod 18, so disposed that upon rotation of said threaded shaft 17, the brackets, and therewith the arms 15 and shoes 10, will be moved longitudinally of the drawing pot or the space left as aforesaid between the covers 6, through which the sheet of glass is designed to be drawn. The threads on the shaft 17 wherewith the respective brackets 16 engage, are oppositely directed so that the movement of the shoes just described will be towards or from each other at equal rates of speed, depending upon the direction of.rotation of said shaft 17. To facilitate rotation of the shaft it isprovided at one ind with a hand wheel 19, as best shown in ig. 1. L

The threaded shaft 17 and parallel guide shaft 18 are in turn supported by vertically adjustable racks 20 that are slidably held in suitable guides 21, forming part of a supporting framework 22 laterally adjacent, but independent of the drawing pot. Such racks are arranged to be raised or lowered in unison through the medium of pinions 23 that mesh therewith, respectively, said pinions being mounted on the ends of a shaft 24 that is provided with a hand wheel 25 to facilitate its operation.

By means of the several mechanisms just described, forming the supporting means for the shoes 10, it will be seen that the latter may be simultaneously raised or lowered as desired with respect to the level of the bath of molten glass in the drawing pot, also that said shoes may be simultaneously advanced towards, or retracted from, each other, so as to vary the distance therebetween. It will further be understood that the drawing ot and the frame 22 are relatively adjusta le transversely of said drawing pot so as to render it possible to bring the shoes 10in exact alignment over the space between the covers 6, through which the sheet of glass is designed to be drawn.

As previously indicated, for the pur ose of actually drawing the sheet of glass rom the bathfan electrically heated bait, somewhat on the order of that shown in the aforesaid Patent No. 972,615, isemployed. Such bait, in other words, comprises an attenuated metal band or ribbon 30, which, instead of being cylindrical as in the specific construction shown in the aforesaid patent, is rectilinearly disposed, being supported at'longitudinally s aced points from a rigid bar 31 by means 0 bolts 32, the headsof which are slotted to receive the upper'edge of the band, and are firmly riveted or welded thereto, as need not be described in detail. The bar 31 is in turn suspended by means of vertical arms 33 attached to itsrespective ends, said arms having their upper ends 34 bent inwardly so as to detachably engage with suitable hooks 35, equivalent members on a vertically reciprocable frame or cage 36. Said members 35 are not directly attached to the cage, but to a bar or beam 37 pivotally secured thereto about an axis 38 so as to leave said member free to oscillate slightly in the plane of the sheet being drawn. Said members 35 are furthermore electrically insulated from the bar 37 as by interposed sheets of insulating material 39, (see Fig.2), so that a suitable heating electric current may be passed from flexible leads 40 through said arms 33 as well as from the band, so that v the current will of necessity pass through the latter. A transformer 41, whereby current of the proper character for the heating of the band or bait member 30, may be supv plied to said leads-40, ispreferably carried on the same frame or cage 36 with the other parts just described, the necessary current for said transformer being derived from an external. circuit through flexible leads not shown, or otherwise as most convenient.

The frame or cage 36 is supportedso as to be reciprocable along vertical guides 45, as clearly shown in Figs. 1 and 2, such guides extending from a point adjacent the drawing pot toany desired elevation, depending upon the length of sheet which it is desired to draw. Movement of the cage up and downthe ways 45 is effected by means of a cable or rod 46 secured to said cage through the medium of an eye,-said cable being con nected with a winding drum (not shown), or other suitable hoisting mechanism.

Such cable, however, is so arranged with respect to the ways 45 that the bait may beelevated entirely clear of the latter so as to permit said bait to be suspended when desired from a traveling carriage 50, as diagrammatically shown in Fig. 4, suitable trackways 51 being-provided whereby, after the cage is thus suspended from the carriage, itmay be moved along with the attached bait and sheet of glass in a horizontal direc tion from out of alignment with the drawing pot or bath of molten glass. After the sheet'of glass is sufiiciently cooled, except that portion attached to the bait, such por-' tion being maintained in contact with the bait, by maintaining a heating current of electricity through theband 30, the sheet is brought into position over an inclined rest 52 and the carriage then lowered with the sheet slidably resting on such rest as successive portions or sections of the sheetare cut off the lower end of thelatter.

The general mode of o eration of the illustrative apparatus just escribed should be sufliciently apparent from the explanation given of the operation of the several component parts of the apparatus. The bait, consisting, as stated, of a band of uniform thickness, is lowered into a bath of molten glassin the drawing 0t, thereby causing adhesion of glass to said bait. Fol lowing this the bait is heated by passing a suitab at the same time it is raised at the requisite speed to produce a sheet of substantially uniform thickness throughout its transverse extent. speed with which the bait israised will be correlated with the viscosity of the surface of the bath the latter being regulated to a I degree by the disposition of the heat insulating walls .6 above the bath. The width of the sheet moreover is maintained substantially the same as the length of the bait by bringing the electrically heated shoes into adhesive contact with the edges of such eet as it is drawn up between said walls 6. The effect of such adhesive contact of the shoes 10 with the edges of the sheet is graphically portrayed in Fig. 1, Where it will be seen that the tendency of the edges to draw toward each other, due to their more rapid cooling, is controlled and counteracted by the supplemental heating thereof through the medium of said shoes 10, causing such edges to adhere to such shoes in passing the same, following which they will set at a'predetermined and uniform distance from the median line of the sheet. The latter, as it rises above the shoes, accordingly is not only of uniform thickness, but of uniform width and-has its edges smoothly finished instead of being frayed or checked in cooling, as would be the case were it not for the employment of such shoes or equivalent means.

e electric current therethrough and.

In such drawing operation the After the body of glass in the bath has been substantially entirely drawn or a sheet of desired length has been produced, such sheet is severed from the bath, and the bait, with the sheet attached thereto, is then moved as already described in a horizontal direction from out of alignment with the bath. Thereupon the sheet'is taken down by being cut up in sections, the resulting product being all ready for the finishing stages. J o

Other modes of applying the principle of our invention may be employed instead of the one explained, change being" made as regards the steps or mechanism herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means be employed.

We therefore particularly point out and distinctly claim as our invention 1. The herein described method of drawing sheet glass, which consists in lowering into and raising from a bath of molten lass a horizontally disposed, angularly ad ustable rectilinear bait member having a coefiicient of expansion different from that of glass, and passing a heating electric current through said member, said current being regulated so as to maintain the temperature of said member at such a point that the glass in contact therewith is kept from setting and thus enabled to accommodate itself without ru ture to any relative displacement of sai member incident to a change in. their temperature.

2. The herein described method of drawing sheet glass, which consists in lowering into and raising from a bath of molten glass a horizontally disposed,'angularlyadustable rectilinear metallic bait member having a co-efficient of expansion different from that of glass, and passinga heating electric current through said member, said current being regulated so as to maintain the temperature of said member at such a point thatthe glass in contact therewith is kept from'setting and thus enabled to accommodate itself without rupture to any relative displacement ofsaid member incident to a change in their temperature.

3. The herein described method of draw ing sheet glass, which consists in lowering into and raising from a bath of molten glass a horizontally disposed, angularly adustable rectilinear bait member havin a co-efiicientof expansion'difierent from t at of glass, andpassinga heating electric current through said member, said current be- Y ing regulated so as to maintain the temper- I glass in contact therewith is kept from set ting and thus enabled to accommodate itself without rupture to any relative displace ment of said member incident to a'change in their temperature, said bait member being thus raised at a speed such as to produce a substantially uniform thickness in the sheet of glass, and thereupon severing such sheet from the bath and moving said bait with sheet thus attached in'a horizontal direction a from out of alignment with such bath.

5. The herein described method of draw ing sheet glass, which consists in lowering into and raising from a bath of molten glass a rectilinear bait member having aco-efficient of expansion different from that of and passing a heating electric current through said member, said current being regulated so as to maintain the temperature of 'said member at such a point that the glass in contact therewith is kept from setting and thus enabled to accommodate itself without rupture to any relative displace ment of said memberincident to a change in their temperature, said bait member being thus raised at a speed such as to produce a substantially uniform thickness in the sheet of glass, and thereupon severing such sheet from the bath, movin said bait with sheet thus attached in a horizontal direction from out of alignment with such bath, and cutting successive portions of desired length from the lower end of said sheet.

6. The herein described method of draw ing sheet glass, which consists in lowering into and raising from a bath of molten glass a rectilinear bait member having a co-efficient of expansion different from that of glass, and assing a heating electric current throug said member, said current being regulated so as to maintain thetemperature of said member at such a point that the glass in contact therewith is kept from setting and thus enabled to accommodate itself without rupture to any relative displacement of said member incident to a change in their temperature, said bait member being thus raised at a speed such as to produce a substantially uniform thickness in the sheet of glass, and thereupon severing such sheet from the bath, moving said baitwith sheet thus attached in a horizontal'direction from out of alignment with such bath, inclining said sheet at a slight angle against a suitable support, and cutting successive portions of desired length from the lower end of said sheet.

7. The herein described method of drawing sheet glass, which consists in lowering into and raising from a bath of molten glass a rectilinear bait-member, and at the same time maintaining the side edges of said sheet adjacent the bath inadhesivecon tact with members normally stationary relatively to said sheet, and spaced from the surface of said bath, whereby the width of the sheet is maintained substantially constant.

8. The herein described method of drawing sheet glass, which consists in lowering into and raising from a bath of molten glass a rectilinear bait-member, and at the same time maintaining the edges of said sheet adjacent the bath in adhesive contact with members normally stationary relatively to said sheet, whereby the width of the sheet is maintained substantially constant, said members being heated to insure such adhesive contact.

9. The herein described method of drawing sheet glass, which consists in lowering into and raising from a bath of molten glass a rectilinear bait-member, and at the same time maintaining the edges of said sheet adjacent the bath' in adhesive contact with members normally stationary relatively to said sheet, whereby the width of the sheet is maintained substantially constant, said membersbeing electrically heated to insure su'ch adhesive contact. a

, 10. The herein described method of drawing sheet glass, which consists in lowering into and raising from a bath of molten glass a'rectilinear bait member having a co-efficient of expansion difi'erent from that of glass, and passing a heating electric current through said member, said current being regulated so as to maintain the temperature of said member at such a point that the glass in contact therewith is kept from setting and thusenabled to accommodate itself without rupture "to any relative displacement of said member incident to a change in their temperature, the edges of said sheet adjacent the bath being at the same time maintained in adhesive contact with members normally stationary relatively to said sheet, whereby the width of the sheet is maintained substantially constant.

11. In apparatus of the character described, the combination with a bath of molten glass, of a vertically reciprocable, horizontally disposed, ailgularly adjustable rectilinear bait member adapted to be lowered into and raised from such bath, said bait member having a co-efficient of expansion different from that of glass, and means adapted to pass a heating electriccurrent through said bait member as it is raised.

12. In apparatus of the character described, the combination with a bath of molten glass, of a vertically reciprocable, rectilinear bait, member adapted to be lowered into and raised from such bath, said bait member having a co-efiicient of expansion different from that of glass, means adapted to pass a heating electric current through said bait member as'it is raised, and normally stationary members locatedover said bath and adaptedto contact with the edges of a sheet of glass being drawn upwardly therefrom by said bait-member. 1

13. In apparatus of the character de scribed, the combination with a' bath of molten glass, of a vertically reciprocable, rectilinear bait member adapted to be flowered into and raised from such bath, said'bait member having a co-eflicient of expansion different from that of glass, means adapted to pass a heating electric current through said baitmember as it is raised, and normal- 1y stationary -members transversely adjust- .able over said bath and adapted to contact with the edges of a sheet of glass being drawn upwardly therefrom by said bait member. 1

14. In apparatus of the character described, the combination ,with a bath of molten glass, of a vertically reciprocable, rectilinear bait member adapted to be lowered into and raised from such bath, said bait member having a co-eflicient of expansion difierent from that of glass, means adapted.

to pass a heating electric current through saidbait member as it is raised, and normal-' ly stationary members vertically adjustable over said bath and adapted to contact with the edges of a sheet ,of glass being drawn upwardly therefrom by said bait member.

15. In. apparatus of the. character described, the combination with a bath of molten glass, of a vertically reciprocable, rectilinear bait member adapted to be lowered into and raised from such bath, said bait member having a co-efiicient of expansion different from that of glass, means adapted to pass a heating electric current through said bait member as it is raised, and normally stationary members independently vertically and transversely adjustable-over said bathand adapted to contact with the edges of a sheet of glass being drawn upwardly."

therefrom by said bait member.

16. In apparatus of the character described, the combination with a bath of molten glass, of a vertically reciprocable, rectilinear bait member adapted to be lowered into and raised from such bath, said bait member having a-co-efiicient of expansion different from that of glass, means adapted to pass a heating electric current through said bait member as it is raised, normally stationary members located over said bath and adapted to contact with the. edges of a sheet scribed, the combination with a bath'* of .molten glass, of a vertically reciprocable, rectilinear bait member adapted to be lowered into .and raised from such bath, said .bait member having a co-eificient of expansion different from that of glass, means adapted to passa heating electric current throu h said bait member as it is raised, norma y stationary members located over said bath and adapted to contact with the edges of a sheet of glass being drawn upwardly therefrom by said bait member, and means for passing a heating electric current through said last-named members.

18. In apparatus of the character described, the combination with a bath of molten glass, of a vertically reciprocable frame, a horizontallydisposed, angularly adjustable rectilinear bait member detachably secured to said frame and adapted to be lowered into and raised from-such bath, said bait member having a co-efficient of expansion different from that of glass, and means adapted to pass a heating electric current through said bait member as it is raised.

19. In apparatus v of the character described, the combination with a bath of, molten glass, of a vertically reciprocable frame, a horizontally disposed, angularly adjustable rectilinear bait member pivotall'y attached to said frame about atransverse axis and adapted to be lowered into and raised from such bath, said bait memberhaving a co-efficient of expansion different from that of glass, and means adapted to pass a heating electric current through said bait member as it is missed. I

20. Inapparatus of the character described, the combination with a bathof molten glass, of "a vertically reciprocable frame, a bar pivotally attached intermediate of its ends a out a transverse axis to said frame, depending members at the respective ends of said bar, a rectilinear bait member detachably secured to said depending members and adapted to be lowered into and raised from such. bath, said bait member having a co-efiicient of expansion different from that of glass, and means adapted to pass a heating electric current through said bait member as it is raised. A

Signed by us, this 9th day of January, 

